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Trigonometry - Form 3

Introduction to sine, cosine, tangent, and solving right-angled triangles.


📘 Topic Summary

Trigonometry is a branch of mathematics that deals with the relationships between the angles and side lengths of triangles. In this study guide, we will explore the basics of trigonometry, including the definitions of sine, cosine, and tangent, as well as how to solve right-angled triangles.

📖 Glossary
  • Sine: The ratio of the opposite side to the hypotenuse in a right triangle.
  • Cosine: The ratio of the adjacent side to the hypotenuse in a right triangle.
  • Tangent: The ratio of the opposite side to the adjacent side in a right triangle.
  • Right-angled triangle: A triangle with one angle that is 90 degrees (a square corner).
  • Hypotenuse: The longest side of a right-angled triangle, opposite the right angle.
⭐ Key Points
  • Trigonometry is used to solve problems involving triangles.
  • Sine, cosine, and tangent are all ratios that relate to the angles and side lengths of triangles.
  • Right-angled triangles can be solved using the Pythagorean theorem.
  • The sine, cosine, and tangent functions have many real-world applications, such as navigation and physics.
  • Trigonometry is used in many fields, including engineering, architecture, and computer science.
🔍 Subtopics
Introduction to Trigonometry

Trigonometry is a branch of mathematics that deals with the relationships between the sides and angles of triangles. It involves the use of right-angled triangles, where one angle is 90 degrees or π/2 radians. The three fundamental trigonometric functions are sine, cosine, and tangent, which are defined as ratios of the opposite side to the hypotenuse, adjacent side, and opposite side respectively.

Solving Right-angled Triangles

To solve a right-angled triangle, you need to know the length of one side and the measure of one angle. You can then use the trigonometric functions to find the lengths of the other two sides. For example, if you know the length of the hypotenuse and one angle, you can use the sine function to find the length of the opposite side.

Using Trigonometry in Real-life Situations

Trigonometry has many practical applications in fields such as navigation, physics, engineering, and computer science. For instance, trigonometric functions are used in GPS systems to determine distances and directions between locations. In physics, trigonometry is used to describe the motion of objects in terms of position, velocity, and acceleration.

Common Applications of Trigonometry

Some common applications of trigonometry include calculating heights and distances in surveying, determining the orientation of a satellite dish, and modeling the motion of objects in physics. Trigonometry is also used in computer graphics to create realistic simulations of 3D environments.

Tips for Solving Trigonometry Problems

When solving trigonometry problems, it's essential to identify the type of triangle involved and choose the correct trigonometric function. You should also make sure to use the correct units and to check your answers for reasonableness. Finally, practice is key to mastering trigonometry.

Common Mistakes to Avoid in Trigonometry

Some common mistakes to avoid in trigonometry include misidentifying the type of triangle or using the wrong trigonometric function. You should also be careful when simplifying expressions and ensure that your answers are reasonable and consistent with the given information.

🧠 Practice Questions
  1. What is the definition of sine in a right triangle?

  2. What is the type of triangle that can be solved using the Pythagorean theorem?

  3. What is the ratio of the opposite side to the adjacent side in a right triangle?

  4. Which field uses trigonometry to determine distances and directions between locations?

  5. What is the longest side of a right-angled triangle, opposite the right angle?

  6. Which trigonometric function is used to find the length of the opposite side in a right triangle?

  7. What is the name of the theorem used to solve right-angled triangles?

  8. Which of the following is NOT a real-world application of trigonometry?

  9. What is the definition of cosine in a right triangle?

  1. Discuss the importance of trigonometry in real-world applications. (20 marks) (20 marks)

  2. Explain how trigonometry is used in navigation. (20 marks) (20 marks)